What Can Be Cause For The Pain In The Neck And Headache?

I have a neck pain almost continuously and most often it is accompanied by the mild to severe headache. In fact, i get up in the morning with a severe neckache. it has been there for the last 6 years. There is general stiffness in the neck though i can rotate my neck in all direction with no single point pain, although with a general tolerable pain.

Also, when I am happy or very excited i dont realise the pain. I have laptop based job and have to travel a lot.

I have done many X-rays in the last several years including a MRI, but nothing of note was found and the doctos just said that I need to correct my posture and excercise. Pl. hbelp me